simplify.c

   1 /*
   2  * Simplify - do instruction simplification before CSE
   3  *
   4  * Copyright (C) 2004 Linus Torvalds
   5  */
   6
   7 #include <assert.h>
   8
   9 #include "parse.h"
  10 #include "expression.h"
  11 #include "linearize.h"
  12 #include "flow.h"
  13
  14 /* Find the trivial parent for a phi-source */
  15 static struct basic_block *phi_parent(struct basic_block *source, pseudo_t pseudo)
  16 {
  17         /* Can't go upwards if the pseudo is defined in the bb it came from.. */
  18         if (pseudo->type == PSEUDO_REG) {
  19                 struct instruction *def = pseudo->def;
  20                 if (def->bb == source)
  21                         return source;
  22         }
  23         if (bb_list_size(source->children) != 1 || bb_list_size(source->parents) != 1)
  24                 return source;
  25         return first_basic_block(source->parents);
  26 }
  27
  28 static void clear_phi(struct instruction *insn)
  29 {
  30         pseudo_t phi;
  31
  32         insn->bb = NULL;
  33         FOR_EACH_PTR(insn->phi_list, phi) {
  34                 *THIS_ADDRESS(phi) = VOID;
  35         } END_FOR_EACH_PTR(phi);
  36 }
  37
  38 static int if_convert_phi(struct instruction *insn)
  39 {
  40         pseudo_t array[3];
  41         struct basic_block *parents[3];
  42         struct basic_block *bb, *bb1, *bb2, *source;
  43         struct instruction *br;
  44         pseudo_t p1, p2;
  45
  46         bb = insn->bb;
  47         if (linearize_ptr_list((struct ptr_list *)insn->phi_list, (void **)array, 3) != 2)
  48                 return 0;
  49         if (linearize_ptr_list((struct ptr_list *)bb->parents, (void **)parents, 3) != 2)
  50                 return 0;
  51         p1 = array[0]->def->src1;
  52         bb1 = array[0]->def->bb;
  53         p2 = array[1]->def->src1;
  54         bb2 = array[1]->def->bb;
  55
  56         /* Only try the simple "direct parents" case */
  57         if ((bb1 != parents[0] || bb2 != parents[1]) &&
  58             (bb1 != parents[1] || bb2 != parents[0]))
  59                 return 0;
  60
  61         /*
  62          * See if we can find a common source for this..
  63          */
  64         source = phi_parent(bb1, p1);
  65         if (source != phi_parent(bb2, p2))
  66                 return 0;
  67
  68         /*
  69          * Cool. We now know that 'source' is the exclusive
  70          * parent of both phi-nodes, so the exit at the
  71          * end of it fully determines which one it is, and
  72          * we can turn it into a select.
  73          *
  74          * HOWEVER, right now we only handle regular
  75          * conditional branches. No multijumps or computed
  76          * stuff. Verify that here.
  77          */
  78         br = last_instruction(source->insns);
  79         if (!br || br->opcode != OP_BR)
  80                 return 0;
  81
  82         assert(br->cond);
  83         assert(br->bb_false);
  84
  85         /*
  86          * We're in business. Match up true/false with p1/p2.
  87          */
  88         if (br->bb_true == bb2 || br->bb_false == bb1) {
  89                 pseudo_t p = p1;
  90                 p1 = p2;
  91                 p2 = p;
  92         }
  93
  94         /*
  95          * Ok, we can now replace that last
  96          *
  97          *      br cond, a, b
  98          *
  99          * with the sequence
 100          *
 101          *      setcc cond
 102          *      select pseudo, p1, p2
 103          *      br cond, a, b
 104          *
 105          * and remove the phi-node. If it then
 106          * turns out that 'a' or 'b' is entirely
 107          * empty (common case), and now no longer
 108          * a phi-source, we'll be able to simplify
 109          * the conditional branch too.
 110          */
 111         insert_select(source, br, insn, p1, p2);
 112         clear_phi(insn);
 113         return REPEAT_CSE;
 114 }
 115
 116 static int clean_up_phi(struct instruction *insn)
 117 {
 118         pseudo_t phi;
 119         struct instruction *last;
 120         int same;
 121
 122         last = NULL;
 123         same = 1;
 124         FOR_EACH_PTR(insn->phi_list, phi) {
 125                 struct instruction *def;
 126                 if (phi == VOID)
 127                         continue;
 128                 def = phi->def;
 129                 if (def->src1 == VOID || !def->bb)
 130                         continue;
 131                 if (last) {
 132                         if (last->src1 != def->src1)
 133                                 same = 0;
 134                         continue;
 135                 }
 136                 last = def;
 137         } END_FOR_EACH_PTR(phi);
 138
 139         if (same) {
 140                 pseudo_t pseudo = last ? last->src1 : VOID;
 141                 convert_instruction_target(insn, pseudo);
 142                 clear_phi(insn);
 143                 return REPEAT_CSE;
 144         }
 145
 146         return if_convert_phi(insn);
 147 }
 148
 149 static inline void remove_usage(pseudo_t p, pseudo_t *usep)
 150 {
 151         if (has_use_list(p)) {
 152                 delete_ptr_list_entry((struct ptr_list **)&p->users, usep, 1);
 153                 if (!p->users)
 154                         kill_instruction(p->def);
 155         }
 156 }
 157
 158 void kill_use(pseudo_t *usep)
 159 {
 160         if (usep) {
 161                 pseudo_t p = *usep;
 162                 *usep = VOID;
 163                 remove_usage(p, usep);
 164         }
 165 }
 166
 167 void kill_instruction(struct instruction *insn)
 168 {
 169         if (!insn || !insn->bb)
 170                 return;
 171
 172         switch (insn->opcode) {
 173         case OP_BINARY ... OP_BINCMP_END:
 174                 insn->bb = NULL;
 175                 kill_use(&insn->src1);
 176                 kill_use(&insn->src2);
 177                 repeat_phase |= REPEAT_CSE;
 178                 return;
 179
 180         case OP_NOT: case OP_NEG:
 181                 insn->bb = NULL;
 182                 kill_use(&insn->src1);
 183                 repeat_phase |= REPEAT_CSE;
 184                 return;
 185
 186         case OP_PHI:
 187                 insn->bb = NULL;
 188                 repeat_phase |= REPEAT_CSE;
 189                 return;
 190
 191          case OP_SYMADDR:
 192                 insn->bb = NULL;
 193                 repeat_phase |= REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 194                 return;
 195         }
 196 }
 197
 198 /*
 199  * Kill trivially dead instructions
 200  */
 201 static int dead_insn(struct instruction *insn, pseudo_t *src1, pseudo_t *src2, pseudo_t *src3)
 202 {
 203         pseudo_t *usep;
 204         FOR_EACH_PTR(insn->target->users, usep) {
 205                 if (*usep != VOID)
 206                         return 0;
 207         } END_FOR_EACH_PTR(usep);
 208
 209         insn->bb = NULL;
 210         kill_use(src1);
 211         kill_use(src2);
 212         kill_use(src3);
 213         return REPEAT_CSE;
 214 }
 215
 216 static inline int constant(pseudo_t pseudo)
 217 {
 218         return pseudo->type == PSEUDO_VAL;
 219 }
 220
 221 static int replace_with_pseudo(struct instruction *insn, pseudo_t pseudo)
 222 {
 223         convert_instruction_target(insn, pseudo);
 224         insn->bb = NULL;
 225         return REPEAT_CSE;
 226 }
 227
 228 static int simplify_constant_rightside(struct instruction *insn)
 229 {
 230         long long value = insn->src2->value;
 231
 232         switch (insn->opcode) {
 233         case OP_SUB:
 234                 if (value) {
 235                         insn->opcode = OP_ADD;
 236                         insn->src2 = value_pseudo(-value);
 237                         return REPEAT_CSE;
 238                 }
 239         /* Fallthrough */
 240         case OP_ADD:
 241         case OP_OR: case OP_XOR:
 242         case OP_SHL:
 243         case OP_LSR: case OP_ASR:
 244                 if (!value)
 245                         return replace_with_pseudo(insn, insn->src1);
 246                 return 0;
 247
 248         case OP_AND:
 249         case OP_MULU: case OP_MULS:
 250                 if (!value)
 251                         return replace_with_pseudo(insn, insn->src2);
 252                 return 0;
 253         }
 254         return 0;
 255 }
 256
 257 static int simplify_constant_leftside(struct instruction *insn)
 258 {
 259         long long value = insn->src1->value;
 260
 261         switch (insn->opcode) {
 262         case OP_ADD: case OP_OR: case OP_XOR:
 263                 if (!value)
 264                         return replace_with_pseudo(insn, insn->src2);
 265                 return 0;
 266
 267         case OP_SHL:
 268         case OP_LSR: case OP_ASR:
 269         case OP_AND:
 270         case OP_MULU: case OP_MULS:
 271                 if (!value)
 272                         return replace_with_pseudo(insn, insn->src1);
 273                 return 0;
 274         }
 275         return 0;
 276 }
 277
 278 static int simplify_constant_binop(struct instruction *insn)
 279 {
 280         /* FIXME! Verify signs and sizes!! */
 281         long long left = insn->src1->value;
 282         long long right = insn->src2->value;
 283         unsigned long long ul, ur;
 284         long long res, mask, bits;
 285
 286         mask = 1ULL << (insn->size-1);
 287         bits = mask | (mask-1);
 288
 289         if (left & mask)
 290                 left |= ~bits;
 291         if (right & mask)
 292                 right |= ~bits;
 293         ul = left & bits;
 294         ur = right & bits;
 295
 296         switch (insn->opcode) {
 297         case OP_ADD:
 298                 res = left + right;
 299                 break;
 300         case OP_SUB:
 301                 res = left - right;
 302                 break;
 303         case OP_MULU:
 304                 res = ul * ur;
 305                 break;
 306         case OP_MULS:
 307                 res = left * right;
 308                 break;
 309         case OP_DIVU:
 310                 if (!ur)
 311                         return 0;
 312                 res = ul / ur;
 313                 break;
 314         case OP_DIVS:
 315                 if (!right)
 316                         return 0;
 317                 res = left / right;
 318                 break;
 319         case OP_MODU:
 320                 if (!ur)
 321                         return 0;
 322                 res = ul % ur;
 323                 break;
 324         case OP_MODS:
 325                 if (!right)
 326                         return 0;
 327                 res = left % right;
 328                 break;
 329         case OP_SHL:
 330                 res = left << right;
 331                 break;
 332         case OP_LSR:
 333                 res = ul >> ur;
 334                 break;
 335         case OP_ASR:
 336                 res = left >> right;
 337                 break;
 338        /* Logical */
 339         case OP_AND:
 340                 res = left & right;
 341                 break;
 342         case OP_OR:
 343                 res = left | right;
 344                 break;
 345         case OP_XOR:
 346                 res = left ^ right;
 347                 break;
 348         case OP_AND_BOOL:
 349                 res = left && right;
 350                 break;
 351         case OP_OR_BOOL:
 352                 res = left || right;
 353                 break;
 354
 355         /* Binary comparison */
 356         case OP_SET_EQ:
 357                 res = left == right;
 358                 break;
 359         case OP_SET_NE:
 360                 res = left != right;
 361                 break;
 362         case OP_SET_LE:
 363                 res = left <= right;
 364                 break;
 365         case OP_SET_GE:
 366                 res = left >= right;
 367                 break;
 368         case OP_SET_LT:
 369                 res = left < right;
 370                 break;
 371         case OP_SET_GT:
 372                 res = left > right;
 373                 break;
 374         case OP_SET_B:
 375                 res = ul < ur;
 376                 break;
 377         case OP_SET_A:
 378                 res = ul > ur;
 379                 break;
 380         case OP_SET_BE:
 381                 res = ul <= ur;
 382                 break;
 383         case OP_SET_AE:
 384                 res = ul >= ur;
 385                 break;
 386         default:
 387                 return 0;
 388         }
 389         res &= bits;
 390
 391         replace_with_pseudo(insn, value_pseudo(res));
 392         return REPEAT_CSE;
 393 }
 394
 395 static int simplify_binop(struct instruction *insn)
 396 {
 397         if (dead_insn(insn, &insn->src1, &insn->src2, NULL))
 398                 return REPEAT_CSE;
 399         if (constant(insn->src1)) {
 400                 if (constant(insn->src2))
 401                         return simplify_constant_binop(insn);
 402                 return simplify_constant_leftside(insn);
 403         }
 404         if (constant(insn->src2))
 405                 return simplify_constant_rightside(insn);
 406         return 0;
 407 }
 408
 409 static void switch_pseudo(pseudo_t *pp1, pseudo_t *pp2)
 410 {
 411         pseudo_t p1 = *pp1, p2 = *pp2;
 412
 413         use_pseudo(p2, pp1);
 414         use_pseudo(p1, pp2);
 415         remove_usage(p1, pp1);
 416         remove_usage(p2, pp2);
 417 }
 418
 419 static int canonical_order(pseudo_t p1, pseudo_t p2)
 420 {
 421         /* symbol/constants on the right */
 422         if (p1->type == PSEUDO_VAL)
 423                 return p2->type == PSEUDO_VAL;
 424
 425         if (p1->type == PSEUDO_SYM)
 426                 return p2->type == PSEUDO_SYM || p2->type == PSEUDO_VAL;
 427
 428         return 1;
 429 }
 430
 431 static int simplify_commutative_binop(struct instruction *insn)
 432 {
 433         if (!canonical_order(insn->src1, insn->src2)) {
 434                 switch_pseudo(&insn->src1, &insn->src2);
 435                 return REPEAT_CSE;
 436         }
 437         return 0;
 438 }
 439
 440 static inline int simple_pseudo(pseudo_t pseudo)
 441 {
 442         return pseudo->type == PSEUDO_VAL || pseudo->type == PSEUDO_SYM;
 443 }
 444
 445 static int simplify_associative_binop(struct instruction *insn)
 446 {
 447         struct instruction *def;
 448         pseudo_t pseudo = insn->src1;
 449
 450         if (!simple_pseudo(insn->src2))
 451                 return 0;
 452         if (pseudo->type != PSEUDO_REG)
 453                 return 0;
 454         def = pseudo->def;
 455         if (def == insn)
 456                 return 0;
 457         if (def->opcode != insn->opcode)
 458                 return 0;
 459         if (!simple_pseudo(def->src2))
 460                 return 0;
 461         if (ptr_list_size((struct ptr_list *)def->target->users) != 1)
 462                 return 0;
 463         switch_pseudo(&def->src1, &insn->src2);
 464         return REPEAT_CSE;
 465 }
 466
 467 static int simplify_constant_unop(struct instruction *insn)
 468 {
 469         long long val = insn->src1->value;
 470         long long res, mask;
 471
 472         switch (insn->opcode) {
 473         case OP_NOT:
 474                 res = ~val;
 475                 break;
 476         case OP_NEG:
 477                 res = -val;
 478                 break;
 479         default:
 480                 return 0;
 481         }
 482         mask = 1ULL << (insn->size-1);
 483         res &= mask | (mask-1);
 484
 485         replace_with_pseudo(insn, value_pseudo(res));
 486         return REPEAT_CSE;
 487 }
 488
 489 static int simplify_unop(struct instruction *insn)
 490 {
 491         if (dead_insn(insn, &insn->src1, NULL, NULL))
 492                 return REPEAT_CSE;
 493         if (constant(insn->src1))
 494                 return simplify_constant_unop(insn);
 495         return 0;
 496 }
 497
 498 static int simplify_one_memop(struct instruction *insn, pseudo_t orig)
 499 {
 500         pseudo_t addr = insn->src;
 501         pseudo_t new, off;
 502
 503         if (addr->type == PSEUDO_REG) {
 504                 struct instruction *def = addr->def;
 505                 if (def->opcode == OP_SYMADDR && def->src) {
 506                         kill_use(&insn->src);
 507                         use_pseudo(def->src, &insn->src);
 508                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 509                 }
 510                 if (def->opcode == OP_ADD) {
 511                         new = def->src1;
 512                         off = def->src2;
 513                         if (constant(off))
 514                                 goto offset;
 515                         new = off;
 516                         off = def->src1;
 517                         if (constant(off))
 518                                 goto offset;
 519                         return 0;
 520                 }
 521         }
 522         return 0;
 523
 524 offset:
 525         /* Invalid code */
 526         if (new == orig) {
 527                 if (new == VOID)
 528                         return 0;
 529                 new = VOID;
 530                 warning(insn->bb->pos, "crazy programmer");
 531         }
 532         insn->offset += off->value;
 533         use_pseudo(new, &insn->src);
 534         remove_usage(addr, &insn->src);
 535         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 536 }
 537
 538 /*
 539  * We walk the whole chain of adds/subs backwards. That's not
 540  * only more efficient, but it allows us to find looops.
 541  */
 542 static int simplify_memop(struct instruction *insn)
 543 {
 544         int one, ret = 0;
 545         pseudo_t orig = insn->src;
 546
 547         do {
 548                 one = simplify_one_memop(insn, orig);
 549                 ret |= one;
 550         } while (one);
 551         return ret;
 552 }
 553
 554 static int simplify_cast(struct instruction *insn)
 555 {
 556         int orig_size;
 557
 558         if (dead_insn(insn, &insn->src, NULL, NULL))
 559                 return REPEAT_CSE;
 560         if (0 && insn->opcode == OP_PTRCAST)
 561                 return 0;
 562         orig_size = insn->orig_type ? insn->orig_type->bit_size : 0;
 563         if (orig_size < 0)
 564                 orig_size = 0;
 565         if (insn->size != orig_size)
 566                 return 0;
 567         return replace_with_pseudo(insn, insn->src);
 568 }
 569
 570 static int simplify_select(struct instruction *insn)
 571 {
 572         pseudo_t cond, src1, src2;
 573
 574         if (dead_insn(insn, &insn->src1, &insn->src2, &insn->src3))
 575                 return REPEAT_CSE;
 576
 577         cond = insn->src1;
 578         src1 = insn->src2;
 579         src2 = insn->src3;
 580         if (constant(cond) || src1 == src2) {
 581                 pseudo_t *kill, take;
 582                 kill_use(&insn->src1);
 583                 take = cond->value ? src1 : src2;
 584                 kill = cond->value ? &insn->src3 : &insn->src2;
 585                 kill_use(kill);
 586                 replace_with_pseudo(insn, take);
 587                 return REPEAT_CSE;
 588         }
 589         if (constant(src1) && constant(src2)) {
 590                 long long val1 = src1->value;
 591                 long long val2 = src2->value;
 592
 593                 /* The pair 0/1 is special - replace with SETNE/SETEQ */
 594                 if ((val1 | val2) == 1) {
 595                         int opcode = OP_SET_EQ;
 596                         if (val1) {
 597                                 src1 = src2;
 598                                 opcode = OP_SET_NE;
 599                         }
 600                         insn->opcode = opcode;
 601                         /* insn->src1 is already cond */
 602                         insn->src2 = src1; /* Zero */
 603                         return REPEAT_CSE;
 604                 }
 605         }
 606         return 0;
 607 }
 608
 609 /*
 610  * Simplify "set_ne/eq $0 + br"
 611  */
 612 static int simplify_cond_branch(struct instruction *br, pseudo_t cond, struct instruction *def, pseudo_t *pp)
 613 {
 614         use_pseudo(*pp, &br->cond);
 615         remove_usage(cond, &br->cond);
 616         if (def->opcode == OP_SET_EQ) {
 617                 struct basic_block *true = br->bb_true;
 618                 struct basic_block *false = br->bb_false;
 619                 br->bb_false = true;
 620                 br->bb_true = false;
 621         }
 622         return REPEAT_CSE;
 623 }
 624
 625 static int simplify_branch(struct instruction *insn)
 626 {
 627         pseudo_t cond = insn->cond;
 628
 629         if (!cond)
 630                 return 0;
 631
 632         /* Constant conditional */
 633         if (constant(cond)) {
 634                 insert_branch(insn->bb, insn, cond->value ? insn->bb_true : insn->bb_false);
 635                 return REPEAT_CSE;
 636         }
 637
 638         /* Same target? */
 639         if (insn->bb_true == insn->bb_false) {
 640                 struct basic_block *bb = insn->bb;
 641                 struct basic_block *target = insn->bb_false;
 642                 remove_bb_from_list(&target->parents, bb, 1);
 643                 remove_bb_from_list(&bb->children, target, 1);
 644                 insn->bb_false = NULL;
 645                 kill_use(&insn->cond);
 646                 insn->cond = NULL;
 647                 return REPEAT_CSE;
 648         }
 649
 650         /* Conditional on a SETNE $0 or SETEQ $0 */
 651         if (cond->type == PSEUDO_REG) {
 652                 struct instruction *def = cond->def;
 653
 654                 if (def->opcode == OP_SET_NE || def->opcode == OP_SET_EQ) {
 655                         if (constant(def->src1) && !def->src1->value)
 656                                 return simplify_cond_branch(insn, cond, def, &def->src2);
 657                         if (constant(def->src2) && !def->src2->value)
 658                                 return simplify_cond_branch(insn, cond, def, &def->src1);
 659                 }
 660                 if (def->opcode == OP_SEL) {
 661                         if (constant(def->src2) && constant(def->src3)) {
 662                                 long long val1 = def->src2->value;
 663                                 long long val2 = def->src3->value;
 664                                 if (!val1 && !val2) {
 665                                         insert_branch(insn->bb, insn, insn->bb_false);
 666                                         return REPEAT_CSE;
 667                                 }
 668                                 if (val1 && val2) {
 669                                         insert_branch(insn->bb, insn, insn->bb_true);
 670                                         return REPEAT_CSE;
 671                                 }
 672                                 if (val2) {
 673                                         struct basic_block *true = insn->bb_true;
 674                                         struct basic_block *false = insn->bb_false;
 675                                         insn->bb_false = true;
 676                                         insn->bb_true = false;
 677                                 }
 678                                 use_pseudo(def->src1, &insn->cond);
 679                                 remove_usage(cond, &insn->cond);
 680                                 return REPEAT_CSE;
 681                         }
 682                 }
 683                 if (def->opcode == OP_CAST) {
 684                         int orig_size = def->orig_type ? def->orig_type->bit_size : 0;
 685                         if (def->size > orig_size) {
 686                                 use_pseudo(def->src, &insn->cond);
 687                                 remove_usage(cond, &insn->cond);
 688                                 return REPEAT_CSE;
 689                         }
 690                 }
 691         }
 692         return 0;
 693 }
 694
 695 static int simplify_switch(struct instruction *insn)
 696 {
 697         pseudo_t cond = insn->cond;
 698         long long val;
 699         struct multijmp *jmp;
 700
 701         if (!constant(cond))
 702                 return 0;
 703         val = insn->cond->value;
 704
 705         FOR_EACH_PTR(insn->multijmp_list, jmp) {
 706                 /* Default case */
 707                 if (jmp->begin > jmp->end)
 708                         goto found;
 709                 if (val >= jmp->begin && val <= jmp->end)
 710                         goto found;
 711         } END_FOR_EACH_PTR(jmp);
 712         warning(insn->bb->pos, "Impossible case statement");
 713         return 0;
 714
 715 found:
 716         insert_branch(insn->bb, insn, jmp->target);
 717         return REPEAT_CSE;
 718 }
 719
 720 int simplify_instruction(struct instruction *insn)
 721 {
 722         if (!insn->bb)
 723                 return 0;
 724         switch (insn->opcode) {
 725         case OP_ADD: case OP_MULS:
 726         case OP_AND: case OP_OR: case OP_XOR:
 727         case OP_AND_BOOL: case OP_OR_BOOL:
 728                 if (simplify_binop(insn))
 729                         return REPEAT_CSE;
 730                 if (simplify_commutative_binop(insn))
 731                         return REPEAT_CSE;
 732                 return simplify_associative_binop(insn);
 733
 734         case OP_MULU:
 735         case OP_SET_EQ: case OP_SET_NE:
 736                 if (simplify_binop(insn))
 737                         return REPEAT_CSE;
 738                 return simplify_commutative_binop(insn);
 739
 740         case OP_SUB:
 741         case OP_DIVU: case OP_DIVS:
 742         case OP_MODU: case OP_MODS:
 743         case OP_SHL:
 744         case OP_LSR: case OP_ASR:
 745         case OP_SET_LE: case OP_SET_GE:
 746         case OP_SET_LT: case OP_SET_GT:
 747         case OP_SET_B:  case OP_SET_A:
 748         case OP_SET_BE: case OP_SET_AE:
 749                 return simplify_binop(insn);
 750
 751         case OP_NOT: case OP_NEG:
 752                 return simplify_unop(insn);
 753         case OP_LOAD: case OP_STORE:
 754                 return simplify_memop(insn);
 755         case OP_SYMADDR:
 756                 if (dead_insn(insn, NULL, NULL, NULL))
 757                         return REPEAT_CSE | REPEAT_SYMBOL_CLEANUP;
 758                 return replace_with_pseudo(insn, insn->symbol);
 759         case OP_PTRCAST:
 760         case OP_CAST:
 761                 return simplify_cast(insn);
 762         case OP_PHI:
 763                 if (dead_insn(insn, NULL, NULL, NULL)) {
 764                         clear_phi(insn);
 765                         return REPEAT_CSE;
 766                 }
 767                 return clean_up_phi(insn);
 768         case OP_PHISOURCE:
 769                 if (dead_insn(insn, &insn->phi_src, NULL, NULL))
 770                         return REPEAT_CSE;
 771                 break;
 772         case OP_SEL:
 773                 return simplify_select(insn);
 774         case OP_BR:
 775                 return simplify_branch(insn);
 776         case OP_SWITCH:
 777                 return simplify_switch(insn);
 778         }
 779         return 0;
 780 }